'fast' and 'CakePHP' shouldn't be used in the same sentence. Cake is great for RAD (Rapid Application Development) but the framework itself is massively bloated to almost the same level as a full CMS. You'll get to market faster, but you'll also be planning a rewrite or migration sooner should you enjoy some degree of success.
In almost all cases, the benchmark was done with no caching. I don't know who launches web apps with no caching, but they shouldn't be doing benchmarks.
I don't concede that Cake is slow for any meaningful definition, but as a matter of point - I'll trade faster developers for a couple CPU cycles any day of the week.